Threaded lock washer and method for fabrication thereof

ABSTRACT

The process and apparatus for fabricating a lock washer made of a strip of coil stock material. The fabricating apparatus is a multi-station forming die punch device wherein a strip of material is cut from stock and wound on a mandrel; a portion of the washer is axially displaced to engage an adjoining turn for preventing unwinding of the finished product, by the fabricating apparatus, which forms the notches and gripping edges of the washer.

ateiii 1 [451 Sept..2,1975

THREADED LOCK WASHER AND WTHOD FOR FABRICATION THEREOF Howard C. GOlIS,Syosset, NY.

Electrical Fittings Corporation, East Farmingdale, NY.

Filed: Sept. 141, 1971 Appl. No.: 180,337

Related U.S. Application Data Division of Ser. No. 825,382, May 16,1969, Pat. No. 3,608,601, which is a continuation-inpart of Ser. No.703,494, Nov. 13, 1967, Pat. No. 3,453,672.

Inventor:

Assignee:

US. Cl. 10/73; 10/86 B lnt. Cl mm 53/20 Field of Search 10/73, 86 R, 86B; 85/88;

References Cited UNITED STATES PATENTS 7/1966 Gohs 151/37 8/1968 Gohs..151/37 7/1969 Gohs 10/73 Primary ExaminerCharles W. Lanham AssistantExaminerE. M. Combs Attorney, Agent, or F irml-1oward C. Miskin 8Claims, 26 Drawing Figures Lil PATENTED 23375 3,902,209

sum 1 nr 55 INVENTOR. HOWARD C. GOHS BY Ha 4C M;

ATTORNEY PATENTED 2 97 v 3,962,209

sum 2 o INVENTOR. HOWARD C. GOHS H C MM ATTORNEY PATENTED 2W5 3, 9&2209

sum 3 or 5 STE/P GUIDE 46 STOCK 6010A 46 F/GJO THREADED LOCK WASHER ANDMETHOD F OR FABRICATION THEREOF This is a divisional application of Ser.No. 825,382, filed May 16, 1969, now U.S. Pat. No. 3,608,601, which inturn is a continuation-in-part of application Ser. No. 703,494, entitledThreaded Lock Washer and Method for Fabrication Thereof, filed Nov. 13,1967, now U.S. Pat. No. 3,453,672.

This invention relates to threaded lock washers, and more particularlyto threaded lock washers having improved locking characteristics andmethods and equipment for the fabrication thereof.

Threaded lock washers, which are used in the millions each year, areessentially cylindrical bodies each having a threaded central bore andspaced gripping or biting tabs along its outer periphery, There are manyuses for such washers, typical of these being the locking of a threadedpipe to an outlet box. Prior art washers have generally been fabricatedby an appropriate stamping operation on sheet stock.

There are three major problems encountered in the use and fabrication ofprior art lock washers. First, in the stamping operation up to 80% ofthe stock material may be wasted because the material which is punchedout to form the central bore and the rounded periphery configuration iswasted. Second, in the manufacture of the prior art lock washer once thebore is formed it must be threaded, and the threading step is arelatively expensive one from the points of view of the initial cost ofthe threading equipment and the time which is required for theoperation. Third, prior art lock washers are known to often work looseafter attachment to an outlet box or similar device, due primarily tothe difficulty of tapping smooth 100% threads.

In my parent application, Ser. No. 394,160 filed Sept. 3, 1964 andentitled Threaded Lock Washer, now U.S. Pat. No. 3,260,293 there isdisclosed an improved lock washer and a method for its construction. Astrip of flat wire material, with a beveled edge, is wound to form ahelical coil. The coil is wound such that the beveled edge of the stripdefines a central threaded bore. The coil may then be stamped to formthe gripping tabs. This method of fabrication is advantageous for threereasons. Because the wire strips which eventually form the final lockwashers may be cut from sheet stock with very little material beingwasted, a considerable savings is realized in the cost of the material.And because the beveled edge is formed on each strip before the windingoperation, there is no need for the thread ing operation in themanufacturing process. (Additionally, a 100% thread is formed.) As forthe final lock washer itself it is vastly superior to the prior art typeof lock washer. If two turns are made in the winding operation, thefinal washer has the characteristics of two separate washers, one on topof the other. When the combined lock washer is used in practice andtightened to an outlet box, the outer convolution rotates slightly withrespect to the inner convolution which rests against the box wall. Thisslight rotation provides a dual locking characteristic which in theprior art can be obtained only with the use of two separate washers. Asingle washer constructed as described in my aboveidentificd applicationis substantially foolproof from Working loose after attachment.

it has been found that electricians and other persons, when using thelock washer disclosed in my aboveidentified application, are sometimesapt to ruin it. A

lock washer is generally tightened to an outlet box or other wall byplacing a screwdriver against one of the gripping tabs and hitting itwith a hammer. The force applied by the hammer causes the washer to turnon the threaded pipe and the gripping tabs to bite into the box wall. Ifan electrician follows the same procedure when using my abovedescribedlock washer there is no problem. However, it is possible that due to theconstruction of the washer an attempt will be made to tighten it inanother manner. Because the washer is basically a helicallywound stripof flat wire, the surface furthest away from the box wall, the surfacesubject to view during installation, exhibits a cut end of flat wire. Anelectrician is apt to place the tip of the screwdriver against this edgeand strike it with a hammer to force the turning of the washer. In sodoing, the helieally-wound wire may uncoil to too great an extent andthe washer may have to be discarded.

To overcome this problem, my copending application, Ser. No. 534,837,filed March 16, 1966 entitled Threaded Lock Washer and Method ofFabrication Thereof now U.S. Pat. No. 3,397,726, disclosed an improvedlock washer having a locking tab provided on the washer itself. This tabis a radial extension of the lower convolution and is bent upward to fitbetween two of the gripping tabs extending from the upper convolution.The locking tab, in the illustrative embodiment of the invention,engages the upper convolution near its end. This has the effect ofrigidly attaching the end of the upper turn to that part of the wirecoil beneath it. In fact, the entire upper turn is a rigid unit, andeven if the upper edge of the strip is struck, the washer turns withoutunfurling.

Because of the locking tab, however, the manufacturing process requiresmore steps than merely the coiling ofa wire strip followed by thestamping of it to form the gripping tabs. For example, the locking tabmust be bent to engage the upper turn of the coil. And the stampingprocess must not destroy the tab after it is bent, if the bending stepis first, or before it is bent, if the stamping step in first. Moreover,an additional punching operation may be required to form a slot on theside (interior or exterior), of the upper end of the coil into which thebent tab may fit. Thus, all things considered, the manufacturing processfor constructing a helically-wound lock washer with a locking tab isconsiderably more complex than the process for constructing the simplerlock washer disclosed in my aboveidentified application.

It is a general object of this invention to provide a lock washer, and amethod and equipment for the fabrication thereof which are improvementsover those disclosed in my above identified application.

In accordance with the principles of my invention a portion of the turnsof the final coiled configuration is displaced longitudinally afterbeing coiled on a threaded mandrel so that adjoining portions of theturns engage. This displacement may take place while a shearing punchand die forms a series of notches and gripping tabs with biting edges onthe coiled strip. The interactions between the various punches and diesis described in much greater detail below. The displaced portion ofturns urns are so offset and bent that the portion of the upper turnengages the adjoining lower turn, so as to effectively rigidly attachthe upper turn to the lower turn. Then, if the upper turn is struck bythe user, the washer turns without unfurling. Because the upper turn isstill free for relative Slight rotational movement with respect to thelower turn. the dual-locking characteristic of the lock washer is notlost even though the upper turn is in fact a rigid unit. Thus. theoffset portion insures that the washer will not be deformed duringinstallation by an absent-minded technician. without. however.destroying any of the beneficial characteristics of the washer.

Before the flat wire strip is coiled it is necessary to form a beveledV-shape along that edge which will subsequently define the threadedcentral bore. In my above-identified application the strip is shown withsuch a beveled edge. While such an edge may be formed in accordance withprior art techniques l have discovered a particularly advantageousmethod for doing so. The simplest process for forming the beveled edgewould appear to be stamping. or punching. The strip may be placed on adie whose upper surface is flat but inclined upward directly beneath theedge of the strip to be beveled. A shear punch may then be forceddownward against the strip, the lower surface of this punch being flatbut inclined downward directly above that edge of the strip to bebeveled. When the die and punch surfaces come against each other thebeveled edge will be formed from the previously straight edge. Thisdeceptively simple process has one major drawback. In forming thebeveled edge the wire material is not cut away but merely squeezedtogether. The material must flow somewhere. Unfortunately the materialis apt to flow in such a manner that the punch is pushed away from thedie. The force which is generated by the flowing metal is exceedinglylarge. In fact, early punches used experimentally in this manner flewoff the die with considerable force when contact was made; the heavysecuring bolts were completely severed.

To overcome this difficulty I provide a groove or indentation in theshear punch mechanism. The mechanism consists of a vertically flatblanking punch having various punch forms thereon and at its upper endthe beveled-edge forming shear punch. The sheet stock is first fed upagainst the flat blank wall of the punch. This wall is used as a stop toobtain the exact width of material rcquired. As the mechanism in loweredthe flat blanking punch fits flush against the vertical end of the die,on top of which rests the sheet stock from which the wire strip is to beformed. As the blanking punch falls the various punch forms cut roundedends and the tab slot on the sheet stock. As the blanking punchcontinues to fall the shear punch strikes the sheet stock and exposesthe recess to cut off a strip and at the same time to form a bevelededge. It is at this time that the strip would be forced out against theblanking punch to break the securing bolts. To eliminate this problemthe blanking punch is provided with a groove or recess into which themetal may flow as the strip grows in width. Because the groove isincluded in the blanking punch it is possible to utilize a simplepunching mechanism for forming the rounded edges. the locking tab slot.and the beveled edge all in a single operation.

It is a feature of this invention to provide a lock washer havinggripping tabs and a screw-threaded cen tral bore, with a plurality ofheIicaIly-coiled wire strip convolutions having a portion of the turnslongitudinally offset and bent for securing the upper end of the wirestrip to the strip material beneath it.

It is another feature of this invention to provide a series of apparatusinteracting with each other in such a manner that the wire strip is cutfrom sheet stock. wound and punched such that the final lock washer maybe fabricated in an exceedingly simple and efficient manner.

It is a still further feature of this invention to provide a mechanismfor cutting a wire strip from sheet stock. cutting it with a punch form,and forming with a shear punch a beveled edge thereon. all in a singleoperation.

Further objects, features and advantages of the invention will becomeapparent upon consideration of the following detailed description inconjunction with the drawing in which:

FIG. 1 is a perspective view illustrating a helical coil of flat wirematerial employed to form a lock washer in accordance with the inventiondisclosed in my aboveidentified parent application;

FIG. 2 is a perspective view of the final lock washer constructed fromthe helical coil of FIG. 1, and disclosed in my above-identified parentapplication;

FIG. 3 is a perspective view of a final lock washer constructed inaccordance with the invention disclosed in my above-identifiedapplication;

FIG. 4 is a sectional view of the lock washer taken along line 4-4 ofFIG. 3;

FIG. 5 is a perspective view of a lock washer constructed in accordancewith the principles of the present invention;

FIG. 6 is a top plan view of the lock washer of FIG.

FIG. 6A is a bottom plan view of the lock washer of FIG. 5;

FIG. 7 is an elevational view of the lock washer of FIG. 5;

FIG. 8 is a sectional view of the lock washer of FIG. 5 taken along theline 8-8 in FIG. 6; and

FIGS. 925 depict illustrative mechanisms for constructing the lockwasher of FIG. 3.

Like numbers refer to like elements in the various embodiments.

In my above-identified application the first step in constructing thelock washer of FIG. 2 is to form a helical coil 30 from a straight stripof stock material as shown in FIG. 1. The material is substantiallyrectangu lar in crossection, except that one lengthwise edge 3] isbeveled. As the strip is wound a screw-threaded central bore is formed.The coil is then stamped or punched on a die. Notchcs 32 are cut outalong the outer periphery of the coil. In addition. in the same step theremaining material at the periphery of the unit is bent slightly to formgripping teeth or tabs 33. The over-all assembly is similar to that ofthe prior art. But the only wasted material is that cut out of notches32. And because of the initial beveled edge of the wire strip 30, whichstrip is used to form the washer. a threading operation is not required.In addition to the advantages in the fabrication of the washer. thecompleted washer exhibits an unusual characteristic it functions inpractice as two separate lock washers. As the washer is turned clockwisefrom above. the teeth of the lower turn of the helix grip the connectingsurface. such as the wall of an outlet box. After the lower convolutionstops turning the upper convolution still turns slightly if sufficientforce is applied. While it may rotate only slightly with respect to thelower turn. it functions as a second lock washer. This dual lockingcharacteristic is described in greater detail in my above-identifiedparent application.

In practice, the washer is tightened by placing the tip of a screwdriverin one of the notches 32 against the upper section of one of thegripping tabs. As the screwdriver is struck with a hammer the washer isturned. It should be noted, however, that end 34 of the metal strip isin full view at the top of the washer. An absent minded individual mightmistakenly place the screw driver against this edge rather than againstone of the biting tabs. In such a case, if sufficient force is applied,after the teeth grip the outlet box wall the washer may unravel and haveto be discarded.

To eliminate this possibility the improved lock washer of theabove-identified application Ser. No. 534,837 shown in FIGS. 3-4, isdifferent from the washer of FIG. 2 in two major respects. First, end 36in FIG. 3 is rounded rather than being straight as is end 34 in FIG. 2.(The lower end of the coil can also be rounded, although this is not asimportant.) With a rounded edge the installer is more likely to placehis screwdriver against the biting edges. But this is not a sufficientguarantee and for this reason my improved washer includes a locking tab35. With this tab it may not even be necessary to provide a rounded edgebecause the tab prevents the uncoiling of the washer even if the upperend of the helix is struck.

While the six notches of the washer of FIG. 2 are formed by punchingthrough the entire coil at six sections on its periphery. in the washerof FIG. 3 only five of these notches are formed. The sixth notch issimilar to the other five only in that the upper turn of the wire stripis cut through. The material in the lower turn directly beneath thehalf-notch is not cut out. Instead, it is bent up into the notch (slot)in the upper turn, as shown in FIG. 4. Thus, the upper end of the coilis in effect locked to the material directly underneath it and cannotunravel if it is struck at its end 36.

Although the construction of this washer is easily un derstood it isreadily apparent that the method for mak ing it is considerably morecomplex than that required for fabricating the washer of FIG. 2. Afterthe wire strip is wound it is not sufficient to provide a singlepunching operation. The problem arises with the notch in the upper turnnear edge 36. While this notch must be cut out, the material below it,which forms locking tab 35, must not be cut out. It is difficult tobuild a punch which will form five full notches 32 and an additionalhalf-notch. Moreover, even after the half-notch is formed a punchingoperation is required to form the locking tab 35 itself. This requires aseparate operation as taught in the prior application.

To avoid the complex method of producing the lock washer shown in FIGS.3 and 4 and yet produce a rigid lock washer, which will not unravel,even if end 34 is struck inadvertently, the improved lock washer of thepresent invention is shown in FIGS. 5-8, and differs from the washers ofFIGS. 2 and 3 by displacing a portion I of the. turns axially orlongitudinally and bending the ends of this portion, so that at leastone end 102 ofthe top turn of this portion is aligned with the bottomturn of the washer adjacent this displaced portion, indicated at I04.Because the top turn is then rigidly attached to the bottom turn, end 34may be straight as in the lock washer of FIG. 2. However, the end can berounded, as at 36 if desired. but this will require a separate punchingstep. The washer of FIG. has five notches 32 formed by punching throughthe entire coil at five sections on its periphery, with portionoverlapping two consecutive tabs 33. All of this punching and bending isdone in one operation. Opposite ends of portion 100 are bent downwardly,such as shown at 106 and 108, so that the end 102 of the top turn ofportion 100 is aligned with the facing end 104 of the bottom turn of tab33. Thus, the upper end of the coil is in effect locked to the materialdirectly underneath it and cannot unravel, if it is struck at its end34, since end 102 of the top turn of portion 100 will engage end 104 ofthe bottom turn. The washer still exhibits the duallockingcharacteristic. The upper washer is a rigid unit which can be viewedbest by following the helix of FIG. 1 from end 34 all the way around toapproximately that part indicated at 38. The second washer extends fromthis point to the lower end of the helical strip. These two washers canmove slightly relative to each other. FIGS. 6, 6A and 7, show threedifferent views of the washer. In FIGS. 7 and 8 a considerable space isshown between the coil layers. In construction, this dimension would beminimal but it is shown exaggerated in the drawing for the sake ofclarity.

The strip 30 which is used to form the lock washer is shown in FIG. 12.This strip is cut from sheet stock, and the lengthwise edge 31 isbeveled. If the strip of FIG. 12 is wound as shown in FIGS. 1, 3 or 5,it is evident that in the teeth forming step, it is only necessary topunch out five full notches 32. Simultaneously, portion 100 is punchedand bent as shown. The locking portion 100 may be constructed merely bycutting and bending that portion of strip 30 overlapping two adjacentgripping tabs 33 in the wound configuration. Thus, the first step in theprocess is to form the strip 30 shown in FIG. 12. The strip is thenwound, and following the formation of the coil the five notches 32 arepunched out and the locking portion 100 is bent down. The variousfigures on sheet 2 of the drawing show the method for obtaining stockstrip 30. Sheet 3 of the drawing shows the manner in which the strip maybe wound on a mandrel. The remaining figures show how notches 32,gripping tabs 33 and locking portion 100 may be formed while the helicalcoil is contained on the same mandrel.

Referring to FIG. 9 it is seen that sheet stock 45 is moved along theupper surface of die 48 toward blanking punch 40. The blanking punchfits snugly against the vertical end of the die. The upper rear end 49of the die has a shape which is shown most clearly in FIG. 1 1. It isflat near the blanking punch and inclined upward slightly away from it.Sheet stock 45 must slide over the little hump thus formed on the uppersurface of die 48. For this reason within strip guides 46 there are twostock lift pads 47. These pads not only minimize the friction of thesheet stock against the die, but in addition lift the stock sufficientlysuch that it slides over the hump and comes to rest against blankingpunch 40.

As punch 40 is forced down, the cutting edge of shear punch 41 bitesinto the sheet stock. As seen most clearly from the perspective view ofFIG. 10 and the side view of FIG. 11, shear punch 41 and die 48 causestrip 30 to be cut from the sheet stock and at the same time to have itsedge 31 beveled.

Recess or groove 42 is included in the blanking punch as shown in FIGS.8-11. In the formation of the beveled edge the strip material issqueezed. The metal must flow somewhere, and in fact it is projected ina horizontal direction toward the blanking punch. Without recess 42 theflowing metal is forced against blanking punch with such force that thepunch may be broken off whatever mechanism (not shown) holds it in placeagainst die 48. Because of the positioning of recess 42, however, in theblanking punch just below the lower surface of the shear punch, thesqueezed metal flows into the recess as shown in FIG. 11 withoutapplying any force against the blanking punch. Thus, in a single step,the falling motion of the punch unit, the strip 30 of FIG. 12 iscompletely formed with its beveled edge.

The blanking punch is preferably not raised at this time for the purposeof gaining access to the cut strip 30. Because the outer edge of thestrip is fitted into recess 42, it may not be advisable to lift theblanking punch to gain access to strip 30. Instead, the punch remainsstationary and a pusher rod used to push the strip out from betweenshear punch 41 and die 48.

FIGS. 911 merely show illustrative apparatus to carry out the first stepin the over-all process of fabricating the lock washer of FIG. 5,namely, the formation of the strip 30 as shown in FIG. 12. The remainingFIGS. 13-28 show illustrative apparatus for performing the remainingsteps in the fabrication process.

FIG. 13 illustrates generally the manner in which the various steps ofmy method of fabrication are carried out. Circular platform 70 containsthree punch end mandrel assemblies, to be described in greater detailbelow. Only the upper portions of mandrels 57 are shown in FIG. 13. Theplatform rotates and makes one complete revolution in three steps. Ateach of the three stations certain operations are performed. In theremaining figures of the drawing various units are shown as operatingupon strip 30. Some of these mechanisms are included in the three punchand mandrel assemblies, which move from station to station. Others,however, are unique to individual stations. While various units areshown in the drawing, and described as being included at particularstations, the mechanisms for operating these units are not shown. Thesemechanisms will be apparent to those skilled in the art.

At station 1 strip 30 is formed as shown by numerals 40, 41, and 46 inFIG. 13. As described above, strip 30 is forced out of the punch and dieassembly and wound around a threaded mandrel 57. A pusher rod 62, asseen in FIGS. 1416, has an end which fits flush against end 34 of strip30. The pusher rod has the same cross-section as strip 30 and,consequently, can move between shear punch 41 and die 48 to force thestrip around the mandrel.

Threaded mandrel 57 includes a shaft which is ex tended through a centerbore in shearing punch 56. The details of the shearing punch and theadditional units between the mandrel and platform 70 need not beunderstood at this point for an appreciation of the manner in which thestrip is coiled around the mandrel. At station 1 a coiling die 58 islowered around the mandrel and on top ofthis die is placed a plate 59.This is shown most clearly in the perspective drawing of FIG. 18. FIG.17 is a cross-section of the complete unit. with the coiling die 58 andplate 59 lowered into position. seen along line l7l7 of FIG. 14. Asshown in FIGS. 1, 4 and 18 coiling die 58 includes a strip guide 61.Pusher rod 62 forces stock strip 30 into this guide 61 and as it isforced in, it is wound around threaded mandrel 57. Coiling die 58functions to bend the strip into a helical shape as it travels aroundthe grooves in the threaded mandrel. The lower surface of plate 59includes a helical angle guide 60. In forming a helix in the mannerdisclosed in the drawing the most difficult part of the process is atthe beginning. The helical angle guide prevents the front end of thestock strip from rising out of the grooves of the mandrel, and forcesthe strip down as it is pushed in. In FIG. 17 the strip is showncompletely wound.

FIGS. 14-16 show the coiling in three stages. In FIG. 14 the strip isshown just entering strip guide 61. Although the top of shearing punch56 is visible, it need not be considered in the coiling process sincethe strip is wound only around the threaded mandrel which is above theshearing punch as seen in FIG. 17. In FIG. 15 the strip is shownapproximately half-wound. Finally, in FIG. 16 the strip is shown fullywound on the mandrel and resting on top of shearing punch 56. It shouldbe noted that pusher rod 62 is pushed into strip guide 61 far enoughsuch that the top plan view of the wound strip comprises two concentriccircles.

Platform is then rotated and the punch-mandrel assembly is moved tostation 2. FIG. 19 shows the complete assembly with the previously woundhelical coil on the mandrel.

The shearing punch 56 consists of a series of six punch cutters 82, fivenotches 84, and the forming die 110 for locking portion 100, shown mostclearly in FIG. 20. It is at this station that the coiled strip isstamped to form the biting tabs 33, the five notches 32 and the lockingportion 100 of FIG. 5. Shearing punch 56 is di rcctly beneath the lowersurface of coiled strip 30. As seen most clearly in FIG. 22, theshearing punch has six punch cutters 82, five with a sloped edge 83,five separated by notches 84 and two having forming die 110 betweenthem. Die 110 is below the surface of shearing punch 56 a predetermineddistance. One-half of the upper surface of punch 56 is tapered so as toform a wedge-shaped surface 112. This taper is dimensioned to allow forthe height of the end of the bottom tu rn so that the washer remainsflat on punch 56 as seen best in FIGS. 19 and 21. The coiled strip 30 iswound at station 1 such that the bottom end of the strip abuts thehigher part 1 13 of surface 112, as seen best in FIG. 20. Die is forceddown over the threaded mandrel to strike the upper surface of coiiledstrip 30. The die includes six grooves 81, which fit around the sixpunch cutters 82 on the mandrel, and the punch 114 forming portion 100.As die 80 is lowered the five notches 32 in the lock washer are formed.The metal in the coiled strip directly above the five notches 84 in theshearing punch is cut out and falls down as scrap. At the same time thenotches which form the biting tabs are formed. Die 80 appliesconsiderable pressure to the coiled strip on the mandrel as it bearsdown to cut out the notches. The coiled strip is forced down against theupper sur face of shearing punch 56 and edges 83 on the punch cuttersfrom the biting tabs 33.

Die 80 contains punch 114, which has opposite sides downwardly extendingas at 116. Punch 114 extends below the surface of die 80 the samedistance as die 110 extends below the surface of shearing punch 56, soas to deflect portion of the washer axially downwardly a distance equalto a turn of the washer. The upper turn of portion 100 remote from end34 is thus aligned with lower turn, as seen in FIG. 19. The metal stripis cut at the sides of locking portion 100 in order that it be deflecteddownwardly. The two edges 118 and 120 of the locking portion punch 114,FIG. 19, are sharp and serve to cut the sides of the portion 100. Aspunch 114 is lowered, locking portion 100 is formed against die 110 inpunch 56.

Referring to FIG. 20, it will be seen that the interior shape of the diematches the exterior shape of the shearing punch.

FIG. 21 is a sectional view taken along the line 2l21 in FIG. 20, afterthe die has been forced down to cut notches 32 in the washer and to formgripping tabs 33, and locking portion 100. FIG. 21 shows the die fittinginto the shearing punch notches 84. After the biting tabs are formed,the die is raised. The completed lock washer is contained on thethreaded mandrel. It is screwed on, however, and a mechanism must beprovided for screwing it off. This is accomplished at station 3.

Thus far threaded mandrel 57 has been stationary in the over-allprocess. The mandrel, however, is forced up slightly at station 3. Rod85, which connects the mandrel to platform 76, is forced up at station 3as shown in FIG. 23. The purpose of raising the mandrel is to disengagethe completed lock washer from shearing punch 56 to facilitate thescrewing off of the washer from the mandrel. Socket tool 86 is loweredas the mandrel is raised. The socket tool is a cylindrical wrench whoseinner surface matches the outer surface of the lock washer. After thesocket tool is fitted over the washer it is rotated counterclockwise asshown in FIG. 24. As it rotates the washer is screwed off the threadedmandrel. Once it is screwed off the socket tool moves over to a bin, notshown, where the completed lock washer falls down out of the tool. Rod85 is then lowered and platform 70 moves once again to return themandrel-punch assembly to station 1 for the fabrication of another lockwasher.

To eliminate unwinding the washer from the mandrel, a smooth arbor 120may be used, as shown in FIG. 25. Arbor 120 has spring loaded teeth 122radially extending from the periphery of arbor 120 and facing inclockwise direction. Teeth I22 prevent unwinding of the locknut, but yetallows removal of the locknut from the arbor by conventional knockoutpins, not shown.

The various punch and die arrangements disclosed on the drawing areparticularly advantageous because of their low tooling cost. Not only isthere a great savings in the cost of the metal required to make thewashers, since there is very little waste scrap. but in addition theset-up costs are minimal.

What I claim is:

l. A method for making a threaded lock washer, comprising the steps of:

1. cutting a strip of lengthwise material,

2. forming a bevel shape along one of the lengthwise edges of saidstrip.

3. winding said lengthwise material around a threaded mandrel to form ahelical coil with a central threaded opening, said threaded mandrelbeing supported by a shearing punch of large diameter and having aplurality of punch cutters mounted thereon with sloped edges at the topsthereof separated by a series of notches and a locking die mounted onsaid shearing punch which abuts a punch cutter and is positioned belowthe surface of said cutter, said lengthwise material being wound aroundsaid threaded mandrel such that the lowest Ill) turn of said coil abutsthe upper surface of said shearing punch, 4. forcing down on said coiledmaterial die means having a series of grooves conforming to said 5 punchcutters in said shearing punch and a punch mounted on said die meanswhich conforms to the locking die on said shearing punch for cutting outthe material in said coil above the notches in said shearing punch anddeflecting a portion of the upper turn radially to be aligned with thebottom turn, and for causing the remaining material in said lowest turnto conform to the shape of the surface of said shearing punch, and

5. unscrewing said coiled material from said threaded mandrel.

2. A method for making a threaded lock washer,

comprising the steps of:

1. cutting a strip of lengthwise material,

2. forming a bevel shape along one of said lengthwise edges,

3. winding said lengthwise material into a plurality of side-by-sideabutting but relatively slidable turns in accordance with a screw threadconvolution to form a helical coil with a central threaded opening,

4. forming a series of tabs extending radially from the outer peripheryof said turns and bent at an incline with respect to a planeperpendicular to the axis of said central opening, said tabs projectingaxially beyond said lowest turn of said coil, and

5. deflecting a portion of one of said tabs on the uppermost surfaceaxially beyond its lowermost surface to engage and be aligned with a tabon the lowermost turn.

3. A method for making a lock washer, comprising the steps of:

1. cutting a strip of lengthwise material,

2. winding said strip into a plurality of side-by-side abutting butrelatively slidable turns to form a helical coil,

3. deflecting a portion of the material in the uppermost of said turnsto abut a portion of the lowermost turn while simultaneously forming aseries of biting teeth extending radially and axially away from thecenter of said coil.

4. A method for making a threaded lock washer in accordance with claim3, further including the step of:

4. forming a bevel shape along one of the lengthwise edges of saidstrip.

5. An apparatus for making a threaded lock washer from sheet stock,comprising means for cutting a strip of lengthwise material from saidsheet stock, means for forming a bevel shape along one of saidlengthwise edges, a threaded mandrel, a chearing punch having a diameterlarger than the diameter of said threaded mandrel and having a pluralityof punch cutters mounted thereon with sloped edges at the tops thereofseparated by a series of notches, means for winding said lengthwisematerial around said threaded mandrel to 60 form a helical coil with acentral threaded opening, said winding means winding said materialaround said threaded mandrel such that the lowest turn of said coilabuts the upper surface of said shearing punch, a locking die mounted onsaid shearing punch and positioned below the surface thereof andoverlapping two adjoining punch cutters, die means having a series ofgrooves conforming to said punch cutters in said shearing punch forbearing down on said coil to cut out the material in said coil above thenotches in said shearing punch and to cause the remaining material insaid lowest turn to conform to the shape of the upper surface of saidshearing punch, a punch mounted on said die means and vertically alignedwith said locking die on said shearing punch, said punch extendingbeyond the surface of said die means toward said locking die, and meansfor unscrewing said coiled material from said threaded mandrel.

6. An apparatus for making a threaded lock washer from sheet stock,comprising means for cutting a strip of lengthwise material from saidsheet stock, means for forming a bevel shape along one of the lengthwiseedges of said strip, means for winding said lengthwise material to forma helical coil with a central threaded opening defined by the bevelededge of said strip of material, and means for stamping said coiledmaterial to form a series of gripping tabs extending radially andaxially away from the center of said coil.

7. An apparatus for making a threaded lock washer from sheet stock inaccordance with claim 6, wherein said stamping means includes a shearingpunch for supporting said coil and having'a plurality of punch cuttersmounted thereon with sloped edges at the tops thereof separated by aseries of notches with a locking die mounted on said shearing punch andpositioned below the surface of one of said cutters, and die meanshaving inner shape conforming to the exterior shape of said shearingpunch for bearing down on said coil supported by said shearing punch,said die means being further provided with a punch cooperating with saidlocking die for deflecting a portion of the upper turn to engage thelower turn.

8. An apparatus for making a threaded lock washer in claim 6, furtherincluding means for preventing rotation of said coil. said means adaptedto release said coil axially.

1. A method for making a threaded lock washer, comprising the stepsof:
 1. cutting a strip of lengthwise material,
 2. forming a bevel shapealong one of the lengthwise edges of said strip,
 3. winding saidlengthwise material around a threaded mandrel to form a helical coilwith a central threaded opening, said threaded mandrel being supportedby a shearing punch of large diameter and having a plurality of punchcutters mounted thereon with sloped edges at the tops thereof separatedby a series of notches and a locking die mounted on said shearing punchwhich abuts a punch cutter and is positioned below the surface of saidcutter, said lengthwise material being wound around said threadedmandrel such that the lowest turn of said coil abuts the upper surfaceof said shearing punch,
 4. forcing down on said coiled material diemeans having a series of grooves conforming to said punch cutters insaid shearing punch and a punch mounted on said die means which conformsto the locking die on said shearing punch for cutting out the materialin said coil above the notches in said shearing punch and deflecting aportion of the upper turn radially to be aligned with the bottom turn,and for causing the remaining material in said lowest turn to conform tothe shape of the surface of said shearing punch, and
 5. unscrewing saidcoiled material from said threaded mandrel.
 2. forming a bevel shapealong one of the lengthwise edges of said strip,
 2. winding said stripinto a plurality of side-by-side abutting but relatively slidable turnsto form a helical coil,
 2. forming a bevel shape along one of saidlengthwise edges,
 2. A method for making a threaded lock washer,comprising the steps of:
 3. winding said lengthwise material around athreaded mandrel to form a helical coil with a central threaded opening,said threaded mandrel being supported by a shearing punch of largediameter and having a plurality of punch cutters mounted thereon withsloped edges at the tops thereof separated by a series of notches and alocking die mounted on said shearing punch which abuts a punch cutterand is positioned below the surface of said cutter, said lengthwisematerial being wound around said threaded mandrel such that the lowestturn of said coil abuts the upper surface of said shearing punch,
 3. Amethod for making a lock washer, comprising the steps of:
 3. windingsaid lengthwise material into a plurality of side-by-side abutting butrelatively slidable turns in accordance with a screw thread convolutionto form a helical coil with a central threaded opening,
 3. deflecting aportion of the material in the uppermost of said turns to abut a portionof the lowermost turn while simultaneously forming a series of bitingteeth extending radially and axially away from the center of said coil.4. forming a bevel shape along one of the lengthwise edges of saidstrip.
 4. A method for making a threaded lock washer in accordance withclaim 3, further including the step of:
 4. forming a series of tabsextending radially from the outer periphery of said turns and bent at anincline with respect to a plane perpendicular to the axis of saidcentral opening, said tabs projecting axially beyond said lowest turn ofsaid coil, and
 4. forcing down on said coiled material die means havinga series of grooves conforming to said punch cutters in said shearingpunch and a punch mounted on said die means which conforms to thelocking die on said shearing punch for cutting out the material in saidcoil above the notches in said shearing punch and deflecting a portionof the upper turn radially to be aligned with the bottom turn, and forcausing the remaining material in said lowest turn to conform to theshape of the surface of said shearing punch, and
 5. unscrewing saidcoiled material from said threaded mandrel.
 5. deflecting a portion ofone of said tabs on the uppermost surface axially beyond its lowermostsurface to engage and be aligned with a tab on the lowermost turn.
 5. Anapparatus for making a threaded lock washer from sheet stock, comprisingmeans for cutting a strip of lengthwise material from said sheet stock,means for forming a bevel shape along one of said lengthwise edges, athreaded mandrel, a chearing punch having a diameter larger than thediameter of said threaded mandrel and having a plurality of punchcutters mounted thereon with sloped edges at the tops thereof separatedby a series of notches, means for winding said lengthwise materialaround said threaded mandrel to form a helical coil with a centralthreaded opening, said winding means winding said material around saidthreaded mandrel such that the lowest turn of said coil abuts the uppersurface of said shearing punch, a locking die mounted on said shearingpunch and positioned below the surface thereof and overlapping twoadjoining punch cutters, die means having a series of grooves conformingto said punch cutters in said shearing punch for bearing down on saidcoil to cut out the material in said coil above the notcheS in saidshearing punch and to cause the remaining material in said lowest turnto conform to the shape of the upper surface of said shearing punch, apunch mounted on said die means and vertically aligned with said lockingdie on said shearing punch, said punch extending beyond the surface ofsaid die means toward said locking die, and means for unscrewing saidcoiled material from said threaded mandrel.
 6. An apparatus for making athreaded lock washer from sheet stock, comprising means for cutting astrip of lengthwise material from said sheet stock, means for forming abevel shape along one of the lengthwise edges of said strip, means forwinding said lengthwise material to form a helical coil with a centralthreaded opening defined by the beveled edge of said strip of material,and means for stamping said coiled material to form a series of grippingtabs extending radially and axially away from the center of said coil.7. An apparatus for making a threaded lock washer from sheet stock inaccordance with claim 6, wherein said stamping means includes a shearingpunch for supporting said coil and having a plurality of punch cuttersmounted thereon with sloped edges at the tops thereof separated by aseries of notches with a locking die mounted on said shearing punch andpositioned below the surface of one of said cutters, and die meanshaving inner shape conforming to the exterior shape of said shearingpunch for bearing down on said coil supported by said shearing punch,said die means being further provided with a punch cooperating with saidlocking die for deflecting a portion of the upper turn to engage thelower turn.
 8. An apparatus for making a threaded lock washer as inclaim 6, further including means for preventing rotation of said coil,said means adapted to release said coil axially.